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Full text of "Observations on the resistance of concrete to freezing and thawing."

Research and Development Laboratories 

of the 
Portland Cement Association 



RESEARCH DEPARTMENT 



Bulletin 68 



Porosity of Hardened 
Portland Cement Pastes 



L. E, COPELAND 

and 
J. C. HAYES 



March, 1956 



Authorized Reprint of a Copyrighted 

JOURNAL OF THE AMERICAN CONCRETE INSTITUTE 

18263 W. McNichols Rd., Detroit 19, Michigan 
February, 1956; Proceedings Vol. 52, p. 633 



Title No. 52-39 



Porosity of Hardened Portland Cement Pastes 

By L. E. COPELANDt and J. C. HAYES* 

■p 

SYNOPSIS 

Continued study of the properties of hardened poitland cement pastes 
has provided information which makes it possible to estimate porosity of 
pastes more precisely than is possible by using the original equations of Powers 
and Brownyard. The total pore volume of hardened pastes is 0.99 w € . 
Capillary pore volume is the difference between total pore volume and pore 
volume characteristic of the gel in hardened pastes. 

The pore volume of the gel is assumed to be the lowest pore volume that 
has been observed in hardened pastes. The paste with the lowest pore 
volume was made with w /c = 0.235 and cured for 11 years. The gel porosity 
calculated for this paste is 0.26. The average Dumber of layers of water 
molecules on the surface of this saturated gel is 2.38. 



INTRODUCTION 



Definitions of symbols 



a 



€ 

€ 
k 



Vt 

I'c 



= nonevaporable water per gram of 
cement in a completely hydrated paste 

= weight of cement 

= density of a saturated hardened paste 

= porosity of hardened paste 

= ratio of V m to u\ 

= capillary pore volume in hardened 

paste 

= gel pore volume in hardened paste 

= total pore volume in hardened paste 

= specific volume of pure water 

= specific volume of cement 

= specific volume of hydration products 



v t = apparent specific volume of the total 

water 
V = partial specific volume of water 

V m = weight of water required to form an 

adsorbed monolayer over the surface 
in a hardened paste 
= volume of paste 

= weight of evaporable water in the 
hardened paste 
Wn = weight of nonevaporable water in the 

hardened paste 
Wl = weight of total water in the hardened 

paste 



V 



General relationships 

The fact that a hardened portland cement paste that is saturated with water 
can lose all of its evaporable water with only a slight change in volume im- 
plies that the hardened paste is porous. A study of relationships between 

the properties and porosities of hardened pa- >s led Powers and Brownyard 1 
to conclude that there are two classes of pores: (1) gel pores— small pores 



s 



between the gel particles, and (2) capillary pores— pores larger than gel pore: 
which exist between aggregates of gel particles. 

♦Received by the Institute Jan. 27, 1955. Title No. 52-39 is a part of copyrighted Jocbnai oftiir America* 
Concrete Institute. V. 27. No. 6, Feb. IQ5G. Pmceedmps V. 52. Separate pnnto are available at 35 cento 
each. DiscuHion (copies in triplicate) should reach the Institute not later than June 1, l9ob. Address 1820J W . 

McNichols Rd., Detroit 19. Mich. . . 4 n . . ... 

tSesior Research Chemist, Research and Development Division, Portland Cement Assn Chicago II. 
tSenior Research Chemist, Zonolite Co., Chicago, 111. (formerly Assistant Research Chemist. Portland 

Cement Assn.). 

633 



634 JOURNAL OF THE AMERICAN CONCRETE INSTITUTE February 1956 

Some of »li« physical properties of a hardened paste, the permeability to 

sv -, , r example, depend upon the total porosity; other properties, such as 

ompressive strength and resistance to freezing, are related to the capillary 

osity. Therefore, an accurate equation for capillary porosity is necessary 

,. ,„ isely the effect of capillary and gel porosities upon the prop- 

rti< - of tl pasti 

Some of the details of t lie Powers and Brownyard model have been changed 

result of continued research. We have found thai their equation for 

ilating capillary porosity gives negative values in a few instance con- 

uently, the prol of computing I lie i sity from certain readily measured 

, ri . I fche p.i- has been studied further so as to understand the cause 
i i _ itive r< ultfi and to obtain a e accurate equation. 

The nation for ilculating capillary pore volume, i>, given by Powei 
id B wnyard. is 



= - : l + ■ 



■ 



< 1 1 



where ii i ginal net* water content of the fresh paste, vo n is the non- 

tent of the saturated, hardened paste, v t is the minimum 
tpj rent specific volume of the total water that can exist in 

urated : • n is th zje n ber of layere of water in the gel por< 

,,i amount of watei necessary i<» form a monolayer on 
1 to tin le v • ' content ot ihe paste. 

I Hi.- olume ol watei in hardened paste us the difference 

ii the -luii- <ii the i '< ai I the volume «•! the cement n i imams 

led I thi Jit "t \\ both fi and chemically combined, in the 

P l I 



i 



i 






I ilume of th< at* I be ■ afr t change <ti olume ot i hi 

P h n ' _• in i h< weight ot watei it main- at a constant 

1 1 1 • le water con tent 



h of 1 1 Kq I) and t d 1 hal i po ii y "I 

(»1\ -ma i ti mated from i h«- pante* availabh 

1. I. In di • that the partial -p ifi< 

I I l| I p ; ' ' : !• . 

1 1 I pn Foi calculi \uti \»> n I I < « >1 al 

■ j I eqi i I " 1 1 i ot I hi olution b< Id 

.' < d. II lijinc can he - iniated I roil 

d tl lun ' l.< er i 

It i he < na j i j 1 h< -ai • manner I m paf 

•I »ov 



V 

tl i 

i 



POROSITY OF HARDENED PORTLAND CEMENT PASTE 



63 



which contain no capillary pores. The capillary pore volume is simply thi 
difference between the total and gel pore volumes. 



EXPERIMENTAL PROCEDURES 



Materials 



Paste were prepared from five different cements covering a wine ranji 
>ment compositions. The computed potential compound comp ion 
i he cement ire gi\ en in Ta ble I . 

Preparation of samples 



of 

oi 



The pa let u ed in t hi> investigation were, with the exceptions n< ed be! 
mi ed in a vacuum by the method described in a pn ious papei Sinc< 
p i ho prepared were free from air* hubbies, theif water «. tents ould 
determined accurately from simple drying or ignition procedun 

The paste- were cured under wain .t 73 F, in closed gla mold* 

Some ol the results con idered here were obtain I u i pa prepared i 

othei project Although curing pro lun varied, i e was exi I 

include only the results obtained on saturated pastes lh 
eparated into three groups: 



Group I 
i evidence 

a I I 1 1 1 1 \ I e - 1 



These specimens were prepared for permeability udi 



i 



rin 



thai some leaching ol lime i m! alkali occurred duri 



(iroup I The e pastes were prepared to determine th< 
the ipecifii surface ; 1 1 m I the nonevaporable - f t 

nonevaporal »le w a t er a h possible 



P 

icn i rai i 



Group 4 \ eries of specimens were prepared in 1940 in ac< ith tl 

p dure used for autoclave tests of ceme Tin pen ured ii 

inoisl Ho i I duri nil t he first 21 hi and under \\ ah a l ', I until ana, I 



nd of II years Water ement ratios ranged from n 2 i to 0.2o bv ' 
These pastes were not va mm mixed, I -hl\ broli -un i < 



i 

specimens appi kred wet, indicating that thi pecimei i. I 

leaehi occurred during the 11 -year curing period This showri 

paring the chemical analysis oi the cured paste with thi d 

I lie cement 



TABLE 1— PROPERTIES OF CEMENTS USED IN POROSITY INVESTIGATION 



l« 


s i 

nt 

S«l frill I'T fcS 


S| 
v oltn 

ea cm 


1 

1 ■_•■ 1 1 


( 


1 - 


1.^7 

s 
1 
1 


IS 
IS 

1H4KJ 
L84X) 


\ 1 9 
115 

n 

U7 

ill 


1 w 

I 

n 10 


r, m 

i 
II 9 

■ 



' 






i! 













1 




1 


I t 






I 7 






1 ■ - 




_"' 








1 



. VI 






- 



■ 
I 



36 



JOURNAL OF THE AMERICAN CONCRETE INSTITUTE 



February 1 956 



Analytical methods 

The total water content, w h of saturated, hardened pastes prepared by the 
acuum mixinu procedures was calculated directly from the ignition loss it 

]M00 F. oi the pa>te. A correction for the original ignition loss of the cement 

Vi (When the pastes contained air voids, the total water content wa 

und from the sum of noiievaporable water and evaporable water, the latter 

ing de rmined by the procedure described by Powers and Brownyard.-' 
The ■'. tisiti< dp, oi the saturated pastes prepared by the vacuum mixin 
proa dure were determined by a specific gravity balance. This determination 
w m . upon th( sample before it was crushed and dried for other tests. 
I p S : group 3, the density determination was performed on -amp] 

which v i _ undated to eliminate voids. The grinding was done in a con- 
trolled aln I cabinet where the air Was Saturated with water and h 

Nonevaporable water in the mples, to*, was determined from the ignition 
I, t 19001 oi mples dried in an evacuated desiccator connected to a trap 

■ ; bv dry i< i md alcohol. 5 

I i \ J, n\ and total water content oi i uum-mixed, saturated 

km I is i Bible I calculate original water content, < mming thai 

i ii volume chai g< :urs duri i the hydration period. Lei c and Wi 

icp | the wi in of the cemenl and total water, respectively, in the 

I lei I i I Ken 



■ 



i + 






• 






hen ■ the specifii olu i of the cemenl and apparent specific 

ilu i the t .1 \ er, resp tivelj and d, is the paste densit} 

1 ' 



Ii tip 






IX 



■ rhang< luring I h< hydrat ion period 









. i . •. ii and i I he specific ' olunru emi< 












I Mi I •: _' id 






— 



' 



\ 



\ 



UllU 






I . gi> in b ' be right-hand meml i 

I i i that tl wi • ratio u dil] d< ined. 

the p • wen • timated from ■'> i adsorption m< .. 

uiemei s. Tin iioil!lt> <»t ;il< ui- 



TABLE 2— RELATIVE VAPOR PRES- 
SURES OVER SATURATED SOLUTIONS 
OF COMPOUNDS USED FOR RELA- 
TIVE VAPOR PRESSURE CONTROL 



I 



H 



Mi 

1ir« 



i i 



i \,t four di it n it i i vapoi 

prcsHin en d< ine<i h m< 

n t hi • - 'i1 iii' f ■ •' amp i 

d I to i he now 

ite, suspended from nh tig 

lash jack I ...< h j 

uaH'd ;»' the jnti lud 



ii i ;i ii 1 1 rf-n 



POROSITY OF HARDENED PORTLAND CEMENT PASTES 637 

sel containing a saturated solution of a pure compound. The four compounds 
and the relative vapor pressures over their saturated solutions are listed in 
Table 2. 

The two parameters, Y m and C, of the BET adsorption equation 6 were 

calculated from adsorption data. Y m is the amount of water necessary to form 
a complete monolayer over the surface, and C is related to the average heat of 
adsorption in the first laver. 



DISCUSSION 
Total pore volume in hardened pastes 

Powers and Brownyard determined the specific volume of the solid phases 
in hardened pastes by a helium-displacement method and obtained the volume 
of pores from the difference between over-all volume and volume of the solid 

hases. Then from the mass of water in saturated samples they concluded 
that water in gel pores had a smaller specific volume than water in capillary 
pores. The difference between the specific volume of gel and capillary water 
complicated the calculation of porosity of pastes. In an investigation reported 
in another paper we found, by a water-displacement method, that partial 
Bpecific volume of gel water is equal to that of capillary water in saturated 

astes.- This simplifies determination of the total pore volume in hardened 

pastes. 

The pores of a saturated paste are filled with a solution of soluble cement 
constituents, principally alkalies, in chemically tree water. We cannot de- 
termine directly the density of this solution, but we have determined that 
partial specific volume of chemically free water in pastes made from certain 
low-alkali cements is (MM). It is not likely that variations in cement com- 
position, including variations in alkali content, will affect this value appre- 
ciably. Consequently, we can use it to approximate closely the volume of the 
solution in the pores of hardened pastes by calculating the volume occupied by 
chemically free water in saturated paste. This approximation has been applied 
to solutions of KOH and XaOH in the range of concentrations to be expecti 
in hardened pastes. The difference between approximated volume and true 
volume of the solution is less than O.o percent. Even if the concentration of 
alkali in the evaporable water were twice the probable highest concentration. 
the error would be below 1 percent. We believe, therefore, that the error in 
pore volume associated with this approximation is less than 0.5 percent. The 
evaporable water content is assumed to be equal to the chemically free water 
content of hardened pastes. 

In other words, within 0.5 percent, the total pore volume, />,, of a hardened 
paste is equal to the weight of evaporable water in the saturated paste multi- 
plied by 0.99, i.e.. 



p t = 0.99 it-, = 0.99(u>« - Wn) 



(5) 



^mce the water gained by the paste during the curing period is given by 



wt - »•„ = 0.254 w„ (Ref. 2) 



638 



JOURNAL OF THE AMERICAN CONCRETE INSTITUTE 



February 1956 



Cement 




No. 


it 


15754 


0.310 


15756 


. 348 


15758 


0.310 


15761 


o 317 


15703 


374 



TABLE 3— MEAN k VALUES FOR it follows that 

VARIOUS CEMENTS Vt = 0.99(w„ - 74(1/ ) 

Gel pore volume 

Powers and Brownyard concluded 

that the framework of a hardened 
paste was a gel which possessed its 
own characteristic porosity. They 
had evidence that the gel pores could 
hold a quantity of water equal to 4V m , 
or the equivalent, 4/ ,,. The term n of Eq. (1) was thus assigned the value 
of 4 by Powers and Brownyard. 

When the procedure for determining w n was revised,'' it became necessary 
to investigate again the relationship between V m and «*„. The later work 
hows that V m is proportional to w n in pastes made from cements with normal 
( - nd C 3 S contents, but 1\ may not be exactly proportional to w, in paste 
n (< from cements with high (" S contents. Since the departure from pro- 
portionality is small, even if real, we shall ignore it, and use the values of ft 
reporl ed in Table 3 for different cements. These values are different from those 
reported by Powers and Brownyard because of the difference in the method 
of determining w n . The relationship between V m and w n will be discussed in 
moo detail in another paper. 
The proportionality of Y m to w n implies that the specific surface of the hy- 

Iration products is a constant and is independent of the extent of hydration 
of the cement in the paste. Apparently, gel particles do not grow larger as 
hydration proceeds; but new particles, similar in size to those firsl formed, are 

iroduced. It seem- reasonable to suppose that a mechanism thai produces 
gel particles of fairly uniform size should also produce a fairly uniform mode 
of packing these particle-: consequently, the gel would possess a characteristic 
porosity. 

Thi minimum value of the ratio w e /V m for hardened pastes is a measure of 
gel porosity lor pore* of saturated hardened paste are filled with evaporable 

water; and surface area, which is proportional to 1 „,. is due to colloidal hy- 
Iration products comprising the gel. The lowest value of "v/1 .., found for 
] • investigated in this work is 2.38. We have not been aide to establish 
the minimum i due, although the proportionality between Y m and w, implie 
that a gel porosity corresponding to w e , V m ^ 1 musl exist. 

The general results we have obtained in attempt ing to determine a minimum 
value for w, \'„ are illustrated by the following consideration: 
Since 



</•. 



r 



«n 



I \> 



- 1 




(I 



it follows thai if a lower limit 
also exist . In a saturated 




for w, 1 gists, a lower limit for "', u musl 
w t w n is related to the original water-cement 



itio, w, ' . by ihe equation 



POROSITY OF HARDENED PORTLAND CEMENT PASTES 



639 



Fig. 1 relationship 

for pastes of cement 15754 

w 
at two — - levels 



GO 



5.0 



4.0 



W t 



W 



3.0 



n 



2.0 



1.0 



w?=a/J77 



-. O. I64G 












0.2 



4 



0.6 



W 
C 



Wt 

ll'n 



ir„ c 

Wn/C 



+ 0.264 ... .(7; 



From Eq. (7) we should expect then thai the ratio w, w for saturated, 
hardened pastes having the same ir r would lie on a straight line when plotted 
against w /c. The intercept of this line at w a <=o -Tumid be 0.254, and the 
slope I (n\ c). Fig. I is a plot of two sets of data. These data were obtained 
on past< at ages up to 11 years. The point- are close to the theoretical lim 

md show no break, indicating that the minimum > r > "'• has i ot be< n r< :hed. 

The lowest values of ir, u\ were reached after I 1 years; it is aoi likely that 
values appreciably lower than these will ever be reached. It will probably b 
necessary to deduce the minimum values of u\ ir, and w, 1 from othei types 
of measurements. 

The porosity, e. of a hardened paste containing neither unhydrated cemenl 
nor capillary pores is 



O.99i0. 



i ■ 



w t \ 






€ = 



Vh 



( 1 + i)"~ 



4- 0.99 M ' f r u 






{> 



0.99* 



+ 



I 






w here v h is the specific volume of the hydration products and a is I he maximum 
value of w n c. Porosities calculated from Eq. (8) with w, l. =2.38 rang* 
from 0.2b to 0.28 for the cement- studied here. These porosities are close to 
that characteristic of a close-packed system of uniformly sized spheres, 0.26. 

Inequality of particle size in a close-packed system could lead to porosities 



640 JOURNAL OF THE AMERICAN CONCRETE INSTITUTE February 1956 

smaller than 0.2<, and consequently to ratios of wJX m smaller than 2.38. 
We believe, however, that particle size distribution in gels is narrow; thus, 
gel porosity should not fall much below 0.2G. 

Accordingly, the best estimation of p now possible is given by 

p„ = 0.99 X 2MV m = 0.99 X 2.38*u>„ = 2.36/. " ,. (9) 

Capillary pore volume in hardened pastes 

( pillary pnn- in hardened pastes are larger than gel pores. They exist 
as spaci thai have not been filled by gel particles and may be completely 
surrounded by gel. The volume of the capillary pores, p e , is the difference 
ietween the total pore volume of the hardened paste and the gel-pore volunw 
It is calculated by combining Eq. (5) and (9). 

p c = p t - p = 0.99 [w t - (1 + 2.38A-),r,] () 

or 

p c = 0.99 [w - (0.746 4- 2Mk)w n ] 

Porosity of hardened pastes 

The ons given above relate pore volume to nonevaporable water and 

total water in urated, hardened pastes. Usually these quantities are ex- 
prc ed as fractions oi cement content of the pastes. Porosity is the pore 

volume in unit volume of paste and can be calculated from w, C and ir, c by 
multiplying pore volume per unit weight of cement by amount of cement in a 

mit volume of p • The equations for total and capillary porosity are: 



Pt 

e = '— = 0.99 



Wn 

c 






J 1 + — 



(11) 



I = ° 



- ( I + 2.38/ 



1 ^> 



12 



wh - the density and 1 is the volume of the paste. 



REFERENCES 

1. Pov I < and Brownyard, T I. Siu«lu- of tin Physical PropertM >f Harden* 

I Cement P id Joi rnal, Pm V. 13: Oct. 1946, pp. 101-132 Nov. 1946, 

Pi 2 I I'm- pp. h" m Jan. 1947, pp. 549-604; ] 1947, pp. 669-712; Mar. 
pp. sr 380 \|- 1947, pp ! 1-992. 

2. i. I.. E., unpublisl ed ma ipt. • 

3. Pow< 'J' ( I opeland, L. I If . J. ( and Mum, If. M., "Permeabilitj of 
P !' \< I Journal, Nov. L954, Proe. V. 51, pp. 

\ Pow< 3, T I md Brow I, T. I., op pp. 2> . 

5. - ope] I, !.. I ind H • .1 ( iSTM Bulletii No. 194, Dec. 1953, p 7". 

8 En i, 1*. If and Teller, I /< at of A icon Cht ical >'<<< 
\ ■ v p 309. 

For such discussion of this paper as may develop please see Part 2, 
December 1956 Journal. In Proceedings V. 52 discussion immediately 
follows the June 1956 Journal pages. 



Bulletins Published by the 

Research Department 

Research and Development Division 

of the 

Portland Cement Association 



Bulletin 2 



Bulletin 1— "Estimation of Phase Composition of Clinker in the System 3CaO 

Si0 2 -2CaO Si0 2 -3CaO Al20 3 -4Ca0 Ah0 3 Fe 2 3 at Clinkering Temper- 
atures," by L. A. Dahl, May, 1939. 

Reprinted from Rock Products, 41, No. 9, 48; No. 10, 46; No. 11, 42; No. 12. 44 
(1938); 42, No. 1. 68; No. 2, 46; No. 4, 50 (1939). 

-"The Bleeding of Portland Cement Paste, Mortar and Concrete Treated 
as a Special Case of Sedimentation," by T. C. Powers; with an appendix 
by L. A. Dahl; July, 1939. 

-"Rate of Sedimentation: I. Nonflocculated Suspensions of Uniform 
Spheres; II. Suspensions of Uniform-Size Angular Particles; III. 
Concentrated Flocculated Suspensions of Powders"; by Harold H. 
Steinour, October, 1944. 

Reprinted from Industrial and Engineering Chemistry, 36, 618, 840, 901 (1944). 

Bulletin 4— "Further Studies of the Bleeding of Portland Cement Paste," by Harold 

H. Steinour, December, 1945. " 



Bulletin 3 



Bulletin 5 



Bulletin 5A 



Bulletin 6 



Bulletin 7 



Bulletin 



Bulletin 9 



Bulletin 10 



Bulletin 11 



"A Working Hypothesis for Further Studies of Frost Resistance of 
Concrete," by T. C. Powers, February, 1945. 

Reprinted from Journal of the American Concrete Institute (February, 1945); Pro- 
ceedings, 41, 245 (1945). 

Supplement to Bulletin 5; Discussion of the paper "A Working Hy- 
pothesis for Further Studies of Frost Resistance of Concrete," bj 

T. C. Powers; discussion by: Ruth D. Terzaghi, Douglas McHenby, 
H. W. Brewer, A. R. Collins, and Author; March, 1946. 

Reprinted from Journal of the American Concrete Institute Supplement (November 
1945); Proceedings, 41, 272-1 1945). 

"Dynamic Testing of Pavements," by Gerald Pickett, April, 1945. 

Reprinted from Journal of the American Concrete Institute (April, 1945); Proceeding*. 
41, 473 (1945). 

"Equations for Computing Elastic Constants from Flexural and Tor- 
sional Resonant Frequencies of Vibration of Prisms and Cylinders," 

by Gerald Pickett, September, 1945. 

Reprinted from Proceedings, American Society for Testing Materials, 45. 846 (1945); 
discussion, 864. 

"Flexural Vibration of Unrestrained Cylinders and Disks," by Gerald 
Pickett, December, 1945. 

Reprinted from Journal of Applied Physic* , 16, 820 (1945). 

"Should Portland Cement Be Dispersed?" by T. C. Powers. February, 
1946. 

Reprinted from Journal of the American Concrete Institute (November, 194". Pro- 
ceedmgs, 42, 117 (1946). 

"Interpretation of Phase Diagrams of Ternary Systems," by L. A. Dahl, 
March, 1946. 

Reprinted from The Journal of Physical Chemistry, 50. 96 (11)46'. 

"Shrinkage Stresses in Concrete: Part 1— Shrinkage or Swelling , 
Its Effect upon Displacements and Stresses in Slabs and Beams of 
Homogeneous, Isotropic, Elastic Material; Part 2— Application of the 
Theory Presented in Part 1 to Experimental Results"; by Gerald 
Pickett, March, 1946. 

Reprinted from Journal of the Amer n Concrete Institute (January and February. 
1946); Proceeding*. 42. 165. 361 (1946). 



Bulletin 12 



Bulletin 13 



Bulletin 14 



Bulletin 15 



Bulletin 16 



Bulletin 17 



Bulletin 18 



Bulletin 19 



Bulletin 20 



Bulletin 21 



Bulletin 22 



Bulletin 2.t 



Bulletin 24 



Bulletin 25 



Bulletin 26 



"The Influence of Gypsum on the Hydration and Properties of Portland 
Cement Pastes," by William Lerch, March, 1946. 

Reprinted from Proceedings, American Society for Testing Materials, 46, 1251 (1946). 

"Tests of Concretes Containing Air-Entraining Portland Cements or 
Air-Entraining Materials Added to Batch at Mixer," by H. F. Gonner- 
man, April, 1947. 

Reprinted from Journal of the American Concrete Institute (June, 1944 I; Proceedings, 
40, 477 (1944 . also supplementary data and analysis, reprinted from Supplement 
(November, 1<44 ; Proceedings, 40, 508-1 (1944). 

"An Explanation of the Titration Values Obtained in the Merriman 
Sugar-Solubility Test for Portland Cement," by William Lerch, 
March, 1947. 

Reprinted from ASTM Bulletin, No. 145, 62 (March. 1947). 

"The Camera Lucida Method for Measuring Air Voids in Hardened 
Concrete," by George J. Verbe< k, May, 1947. 

Reprinted from Journal of the American Concrete Institute (May, 1947;; Proceedings, 
43, 1025 (1947). 

"Development and Study of Apparatus and Methods for the Determina- 
tion of the Air Content of Fresh Concrete," by Carl A. Menzel, May, 
1947. 

Reprinted from Journal of the American Concrete Institute (May, 1947 ; Proceedings, 
43, 1053 (1947). 

"The Problem of Proportioning Portland Cement Raw Mixtures: 
Part I — A General View of the Problem; Part II — Mathematical Study 
of the Problem; Part III — Application to Typical Processes; Part IV — 
Direct Control of Potential Composition' 1 ; by L. A. Dahi, June, 1947. 

Reprinted from Rock Products, 50, No. 1, 109; No. 2, 107; Xo. 3. 92; Xo. 4. 122 (1947). 

The System CaO-Si0 2 -H20 and the Hydration of the Calcium Sili- 
cates," by Harold H. Steinour, June, 1947. 

Reprinted from Chemical Reviews, 40, 391 (1947). 

"Procedures for Determining the Air Content of Freshly-Mixed Con- 
crete by the Rolling and Pressure Methods/' by Carl A. Mi.n/el, 

June, 1947. 

Reprinted from Proceedings, American Society far Testing Mater < 47, 833 (1947). 

The Effect of Change in Moisture-Content on the Creep of Concrete 
under a Sustained Load," Gerald Pickett, July, 1947. 

Reprinted from Journal of the American Concrete InstituU February, 1942 Pro- 
ceedings, 38, 333 (1942 

Effect of Gypsum Content and Other Factors on Shrinkage of Concrete 
Prisms," by Gerald I kett, October, 1947. 

Reprinted fn Journal of the American Concrete Institute (October, 1947;; Pro- 
ceedings, 44, 149 1 i. 

"Studies of the Physical Properties of Hardened Portland Cement 
Paste," by T. C. Powers and T. L. Brownyahb, March, 1948. 

I • Tinted from Journal of th* < U InetituU October-] embei 1946; 

January-April, 1947 / ?*, 43, 101, 249, 46! 669 845,933 L947). 

"Effect of Carbon Black and Black Iron Oxide on Air Content and Dura- 
bility of Concrete/ 1 In omaf (i. Taylor, Mmv. 1948. 

Reprinted from Journal of the A tie h U Vpril. 1948 Pro />. 

44 • 13 1948 - 

'Effect of Entrained Air on Concretes Made with So-Called 'Sand- 
Graver Aggregates," by Pai i Kliegeb, November, 1948. 

Rep from J f the Amer . Concrete Institute (Oct 1948); Pro- 

ceeding 45. 149 I'M 

A Discussion of Cement Hydration in Relation to the Curing of Con- 
crete/* bj I I Powers, August, 1948. 

Repri i from Pr< JL , Rest h Board, 27, 178 (1947). 

"Long-Time Study of Cement Performance in Concrete." This bulletin 

compr - foui install men the report of this investigation, by 1. R 

M< Mil] v I. L. Tyler, \Y. I . Hansen, William Leech, I I i >bd I 
L S. Brow \. August, 1948. 

from J Febi uai -May, 1 ; 

P 44. J41 7J : ^77 )• 



Bulletin 27 — "Determination of the Air Content of Mortars by the Pressure Method," 

by Thomas G. Taylor, February, 1949. 

Reprinted from ASTM Bulletin, No. 155, 44 (December. 1948). 

Bulletin 28 — "A Polarographic Method for the Direct Determination of Aluminum 

Oxide in Portland Cement," bv C. L. Ford and Lorrayne Le Mar, 
April, 1949. 

Reprinted from ASTM Bulletin, No. 157, 66 (March, 1949). 

-"The Nonevaporable Water Content of Hardened Portland-Cement 
Paste — Its Significance for Concrete Research and Its Methods of 
Determination," by T. C. Powers, June, 1949. 

Reprinted from ASTM Bulletin, No. 158, 68 (May, 1949). 

Bulletin 30 — "Long-Time Study of Cement Performance in Concrete — Chapter 5. 

Concrete Exposed to Sulfate Soils," by F. R, McMillan, T. E. Stanton, 
I. L. Tyler and \Y. C. Hansen, December, 1949. 

Reprinted from a Special Publication of the American Concrete Institute (1949). 

Bulletin 31- 



Bulletin 29 



"Studies of Some Methods of Avoiding the Expansion and Pattern 
Cracking Associated with the Alkali-Aggregate Reaction," by William 
Lerch, February, 1950. 

Reprinted from Special Technical Publication No. 99, published by American Society 
for Testing Materials (1950). 

Bulletin 32 — "Long-Time Study of Cement Performance in Concrete — Chapter 6. 

The Heats of Hydration of the Cements," by George J. Verbeck and 
Cecil W. Foster, October, 1949. 

Reprinted from Proceedings, American Society for Testing Materials, 50, 1235 (1950). 

"The Air Requirement of Frost-Resistant Concrete," by T. C. Powers; 
discussion bv T. F. Willis. 

Reprinted from Proceedings of the Highway Research Board, 29, 1S4 (1949). 

"Aqueous Cementitious Systems Containing Lime and Alumina," 

by Harold H. Steinour, February, 1951. 



Bulletin U 



Bulletin 



Bulletin 35 



Bulletin 36 



Bulletin 37 



Bulletin 38 



"Linear Traverse Technique for Measurement of Air in Hardened 
Concrete," by L. S. Brown and C. U. I'ilrson, February, 1951. 

Reprinted from Journal of the American Concrete Institute (October, 1950); Proceed- 
ings. 47, 117 (1951). 

"Soniscope Tests Concrete Structures," bv E. A. Whitehurst, February, 
1951. 

Reprinted from Journal of the American Concrete Institute (February. 19ol); Pro- 
ceedings 47, 433 (1951). 

"Dilatometer Method for Determination of Thermal Coefficient of 
Expansion of Fine and Coarse Aggregate," by Georoe J. Verbeck and 

Werner E. Hass, September, 1951. 

Reprinted from Proceedings of the Highway Research Board, 30, 187 (1951). 

"Long-Time Studv of Cement Performance in Concrete — Chapter 7. 
New York Test Road," by F. H. Jackson and I. L. Tyler, October, 1951. 

Reprinted from Journal of the American Concrete Institute (June. 1951 ' ; Proceeding* 
47, 773 (1951). 



Bulletin 39 



. t 



Bulletin 40 



Bulletin 41 



Bulletin 42 



Changes in Characteristics of Portland Cement as Exhibited by Lab- 
oratory Tests Over the Period 1904 to 1950," by H. F. Gonnebman and 

William Lerch. 

Reprinted fromSpecial Publication So. t£? published by American Society for Testing 
Materials. 

"Studies of the Effect of Entrained Air on the Strength and Dura- 
bility of Concretes Made with Various Maximum Sizes of Aggregate," 

by Paul Klieger. 

Reprinted from Proceedings of the Highway Research Board. 31. 177 (19 •-' 

"Effect of Settlement of Concrete on Results of Pull-Out Bond Tests," 
by Carl A. Menzel, November, 1952. 

"An Investigation of Bond Anchorage and Related Factors in Rein- 
forced Concrete Beams," by Carl A. Menzel and William M U ood- 
N'ovember, 1952. 



Bulletin 



Bulletin 44 



Bulletin 45 



Bulletin 46 



4 'Ten Year Report on the Long-Time Study of Cement Performance 
in Concrete/' by Advisory Committee of the Long-Time Study of Cement 
Performance in Concrete, R. F. Blanks, Chairman. 

Reprinted from Journal of the American Concrete Institute (March, 1953); Proceedings, 
49, BO! (1953). 

"The Reactions and Thermochemistry of Cement Hydration at Ordi- 
nary Temperature/' by Harold H. Steinour. 

Reprinted from Third International Symposium on the Chemistry of Cement. London* 
Sept. 1952. 

"Investigations of the Hydration Expansion Characteristics of Portland 
Cement/' bv H. R Goxnermax, Wm. Lerch, and Thomas M. Whiteside 
June, 1953. 



"Theory of Volume Changes in Hardened Portland Cement 
During Freezing/' by T. C. Powers and R. A. Helmvth. 

Reprinted from Proceedings of the Highway Research Board, 32 2>o (1953). 



Paste 



Bulletin 47 — "The Determination of Non-Evaporable Water in Hardened Portland 

Cement Paste/' by L. E. Copeland and John C. Hayes. 

Reprinted from ASTM Bulletin No. 194, 70 (December. 1953i. 



Bulletin 48 — "The Heats of Hydration of Tricalcium Silicate and beta-Dicalcium 

Silicate," by Stephen Bri water, J. C. Hayes and \Y. E. Habs. 

Reprinted from The Journal of Physical Chemistry, 58, 279 (1954). 

Bulletin 49 — "Void Spacing as a Basis for Producing Air-Entrained Concrete/' 

by T. C. Powers. 

Reprinted from Journal of the American Concrete Institute (May, I954)j Proceedings, 
50. 741 (1954). 

Bulletin 49A — Discussion of the paper "Void Spacing as a Basis for Producing Air- 
Entrained Concrete/ 1 by J. E. Backstrom, R. \Y. Burrows, V. E. Wolk- 
odoff and Author, T. C. Powers, 

Reprinted from Journal of the American Concrete Institute (Dec. Part 2 1954); Pro- 
ceeding, 50, 760-1 (1954). 

Bulletin 50— "The Hydrates of Magnesium Perchlorate/' by L. E. Copeland and R. 

H. Bragg. 

Reprinted from The Journal of Physical Chi misi // 58. 1075 (1954). 

Bulletin 51 — "Determination of Sodium and Potassium Oxides in Portland Cement 

Raw Materials and Mixtures, and Similar Silicates by Flame Photom- 
etry/' I C. L. Ford. 

Reprinted from Analytical Chemistry, 46, 157S (1954). 

Bulletin 52— "Self Desiccation in Portland Cement Pastes/' by L. E. Copeland and 

R. H. Bragg. 

Reprinted from ASTM Bulletin, No. 204, 34 (February, 1955). 

Bulletin 55— "Permeability of Portland Cement Pastes/' by T.C. Powers, L E. Cope- 
land, J. C. Hayes and II. MM an v 

Reprinted from Journal of the Am an Concrete Institute, f November. 1954); Pro- 
ceedings, 51. 2>i5 (1955). 

Bulletin 54 — "Some Observations on the Mechanics of Alkali-Aggregate Reaction/ 1 

by L. S. Brown. 

Reprinted from ASTM Bui n, No. 205, 40 (April. 1055). 



Bulletin 55 



An Interpretation of Published Researches on the Alkali-Aggregate 
Reaction: Part 1— The Chemical Reactions and Mechanism of Expan- 
sion; Part 2 — A Hypothesis Concerning Safe and Unsafe Reactions 
with Reactive Silica in Concrete/' by T. C. Powers and II H. Steinoub. 

Reprinted from Journal of the American Concrete h te (February and April. 1955); 

Proceedings, 51 197, 785 (1955 



Bulletin 56 



. * 



Comparison of Results of Three Methods for Determining Young's 
Modulus of Elasticity of Concrete/' by U E, Philleo. 

Reprinted from Journal of the American ncrete Institute (January, 1955): Proceed- 

'> M 4ol 1 



Bulletin 57 — "Osmotic Studies and Hypothesis Concerning Alkali-Aggregate Re- 
action/* by <h;orge J. Vekbec k and Charles Gramlkh. 

li( -printed from Proceedings, America* iety / Testing Mi 55, 

Bulletin 58 — "Basic Considerations Pertaining to Freezing and Thawing Tests," b 

T. (\ PoWBBfl 

Reprinted from Proceedings American \fal 55, 



Bulletin 59— "New Study on Reactions in Burning Cement Raw Materials/' 

L. A. I.) A HI* 

Hepnn ted from Rock Product*, 58, No. 5 7! N 102 Wo 7^ 

Bulletin 60 "Long-Time Study of Cement Performance in Concrete Chapter ,J 

Correlation of the Results of Laboratory Tests v\ i t h Field Performam 
Under Natural Freezing and Thawing Conditions," \ I II J v. k \ 

Keprintfd from Journal o '•• \ Concrete! *r 

52, 100 (1956). 

Bulletin 61— "A Method for the Determination of the ( menl Content <»f Plastic 

Concrete/' h\ \\ < . IIimi itrul li \ W in Id 

Reprinted from \8T M Bh No 199, <: i h 

Bulletin 62 — "Investigation of the Franke Method ol Determining I i Calcilll 

Hydroxide and Free Calcium Oxide," by I I Pri "i phen Bri 

\ \ i i it and I ) L, Kani it". 

Reprinted froin Inalytirat ( <mj ( IX) - 



Bulletin 6 A — "Ifydniullc Pressure in Concrete," l>\ I I Po* » » 

Reprinted from P i td I I m* I H ' ' 

Bulletin 64— "The Freezing and Thawing Test," I I ( Po* 

Reprinted from 181 M R#p 

gut* U'\ I 'iition r> ■ 

Bulletin 65 — "The Stoichiometrv of the Hydration of Intalci mi Sitlcal »i Boom 

Temperature: 1 — Hydration In a Ball Mill II — llvdratinn in a Pa 

Form," bj Stephen Bri \ \ • er, L I i II! II I 

Reprinted from / * ' i I 

Bulletin 66 — "Effect of \ugregate on Shrinkage of Concrete and Hypotln ncern 

ing Shrinkage, "bj Gerai d Ph kett. 

Reprinted fi om J I »*< 

i'j 52, p >8I 195*5 

Bulletin 67 — "Observations on the Resistance ol Concrete to h r zing and I haw- 
ing/' l>\ Ih bert Woods [ncludi dis< ion I. E. Baci 
\\ \\ Hi \i\ii )w s, and aul hor'a cIohuj 

IN j printed f n >m / ■ ' m 

SI, 345 I 9 • ■ . I >i l'7 i 5 1 

Bulletin 6H— "Porosity of Hardened Portland Cement Paetee," I I 

I: inted from i ' 

i 'i ■ ,i,